CRISIS is a series that is very well-known in the field, as I've mentioned here before. It was a worlds-shattering storyline, so it's fairly obvious why my teenage self bagged them away very carefully.
But the DC CHALLENGE... Ah. The DC CHALLENGE was a twelve-issue round-robin maxiseries. A different writer/artist team worked on each book, and the premise of the setup was that each issue was supposed to end with a cliffhanger, which the next team had to resolve. Furthermore, if any member of the team was a regular writer of a particular character, they had to avoid using that character in their issue.
I loved this series. It was literally the favorite comic book of my childhood. In fact, if you told me that I was only allowed to keep one comic series from my childhood, this would be the one.
The storyline incorporated dozens of minor characters throughout the DC universe, and the plot twisted around in bizarre ways that made no sense. It was obvious pretty quickly that the story would fit nowhere in DC continuity. But one could see the writers struggling to make the story work, and in the end, even if the story wasn't resolved perfectly, it was obvious that the book was a lot of fun for the creators behind it. (Probably it was a lot of heartache, too, but there it is.)
Sadly for me, most comic fans have forgotten the series or dismiss it as a stunt. I'd love to see DC Comics re-release it as a collected edition, but apparently the market just isn't there. (If anyone out there wants to prove DC wrong, write a letter to them, attention to Editor - Collected Editions. I'd love to see them flooded with requests for it. In fact, I think I'll go write my letter now...)
There's an interesting postscript. Years later, I find myself good friends with bob_greenberger, who was the editor of the book. Bob literally helped put together some of the most memorable stories of my childhood, which means he bears some responsibility for who I am today. (I am sure he is shaking his head as he reads this.)
And, as a second postscript, I routinely read the blog of the man who came up with the idea in the first place: Mark Evanier. He doesn't think it was succesful, but I respectively disagree.
If you want to learn more about the book, see Beek's Books - The DC Challenge! (comicbook reviews).
Now, to go rebag them -- but carefully...